Sausages are made by preparing a meat emulsion, as for frankfurters, or a ground meat mixture, or even a meat and vegetable, such as soy beans, or just a vegetable mixture, and stuffing it into a casing. To get a smoky taste and color, these encased or peeled sausages are smoked with gaseous or liquid wood smoke, by dipping them into a bath of liquid smoke, by spraying or drenching encased sausages with a casing permeable liquid smoke prior to thermal processing. Another way is to use casings that have their interior surfaces coated with a liquid smoke, which color transfers to the sausage filling during the processing cycle.
Frankfurters span a range of colors, from a very light red to a much darker one, depending on where they are sold. Sausages made of coarsely ground meat, such as polish sausages, tend to have a more intense reddish color than does the average frankfurter, but they also come in a range of colors. Each smoked product has its own standards for smoky color and taste.
Differences in color can also be seen in products processed in casings or casing-like mediums, such as sealed bags, which contain whole muscle meats, such as hams or chicken breasts, and cheeses, and that are smoked while inside the casings.
Food casings used in the processed food industry are generally thin-walled tubing of various diameters, typically prepared from cellulose using a number of different processes. Although the vast majority of casings are basically colorless, some do contain coloring agents which transfer to the encased foodstuff upon processing.
In general, food casings are stuffed with foodstuffs such as sausage meats or meat emulsions, and are then heat processed. During the cooking and further processing, if the casing contains a transferable color on its inner surface, color is transferred to the encased foodstuff, thereby coloring the surface of the finished product. After processing, these casings are removed prior to final packaging. These skinless sausages are generally processed in nonfiber-reinforced (“nonfibrous”) cellulose casing. The term “nonfibrous” is used here to mean without use of fiber reinforcement (e.g., a paper tube) in the casing and nonfibrous is most commonly understood in the art to refer to casings without paper or a previously bonded fiber reinforcement. Nonfibrous casings are typically used to process small diameter sausages including polish sausages, wieners, or frankfurters. However, larger diameter sausages such as salami are frequently sold with the casing left on. These sausages are usually packaged in fiber-reinforced (fibrous) cellulosic or nylon casing.
In one well known method of manufacturing of nonfibrous, self-coloring or smoked cellulose sausage casings, viscose is typically extruded through an annular die into a coagulating and regenerating bath to produce a tube of regenerated cellulose. In another method, cellulose is dissolved by a tertiary amine oxide and later, the cellulose is precipitated to form a film or filament, as described in U.S. Pat. No. 2,179,181. This tube is subsequently washed, plasticized, e.g., with glycerine, impregnated with a water-soluble, casing-permeable colorant and dried by inflation under substantial air pressure. After drying, the self-coloring casing is wound on reels and subsequently shirred on high-speed shirring machines, such as those described in U.S. Pat. Nos. 2,984,574; 3,451,827; 3,454,981; 3,454,982; 3,461,484; 3,988,804 and 4,818,551. In the shirring process, typically lengths of from about 40 to about 200 or more feet of casing are compacted (shirred) into tubular sticks of between about 4 and about 30 inches. These shirred casing sticks are packaged and provided to the meat processor who typically causes the casing sticks to be deshirred at extremely high speeds while stuffing the deshirred casing with a meat emulsion. The meat can be subsequently cooked or pasteurized and the casing removed from the meat processed therein with high-speed peeling machines. The resulting peeled sausage is colored by the colorants, such as FD&C dyes, that have transferred from the casing to the surface of the sausage during cooking or pasteurization.
Colorless nonfibrous casings are made in a similar fashion, but without the color additive steps. Smoked foodstuffs may be produced using the clear casings by exposing either the encased or released foodstuff to a liquid smoke solution by drenching, spraying or showering the liquid smoke on the encased or released foodstuff.
For fibrous casing, a process of manufacture similar to that for nonfibrous casing is employed. The viscose is extruded onto one or both sides of a tube formed by folding a web of paper so that the opposing side edges overlap. The viscose impregnates the paper tube and upon coagulation and regeneration of the viscose, a fiber-reinforced tube of regenerated cellulose is produced. Liquid smoke or other colorants may be introduced to the fibrous casing generally by slugging, spraying, drenching or dipping. Fibrous casing is able to absorb much greater amounts of colorants than is nonfibrous casing, due to the additional reinforcing material used in the casing. These colorants or flavorants then transfer to the surface of the product prepared inside the fibrous casing.
Production of both nonfibrous and fibrous casing is well-known in the art and the present invention may utilize such well known processes and casings.
Cellulosic casings are typically humidified to a level sufficient to allow the casing to be shirred without undue breakage from brittleness, yet humidification must be at a level low enough to prevent undue sticking of the casing to the shirring equipment, e.g., the mandrel, during the shirring operation. Often a humectant is employed to moderate the rate of moisture take-up and casing swelling, to produce a casing that during the shirring operation has sufficient flexibility without undue swelling or stickiness. Typically, a lubricant such as an oil will also be used to facilitate passage of the casing through the shirring equipment, e.g. over a shirring mandrel.
It has been useful to lubricate and internally humidify cellulose casings during the shirring process by spraying a mist of water and a stream of lubricant through the shirring mandrel. This is an economical, fast and convenient way to lubricate and/or humidify the casing to increase the flexibility of the casing and facilitate high speed shirring without undue detrimental sticking, tearing or breakage of the casing. Additional components, such as coloring agents, liquid smoke, peeling aids, etc., may be added to the shirring solution, and thereby introduced into the interior of the casing.
In the formation of cellulosic casing an extruded cellulosic film forms what is known as gel stock casing having a high moisture content in excess of 100 wt. %. This gel stock casing is unsuitable for stuffing with food such as meat emulsion, e.g. to form sausages, because it has insufficient strength to maintain control of stuffing diameter and prevent casing failure due to bursting while under normal stuffing pressure. Gel stock casing is typically dried to a moisture level well below 100 wt. %, which causes the cellulose to become more dense with increased intermolecular bonding (increased hydrogen bonding). The moisture level of this dried casing may be adjusted, e.g., by remoisturization, to facilitate stuffing.
In the formation of skinless frankfurters where the casing is removed after processing, sausage proteins coagulate, particularly at the sausage surface, to produce a skin and allow formation of a liquid layer between this formed skin and the casing as described in U.S. Pat. No. 1,631,723 (Freund). In the art, the term “skinless frankfurter” is understood to mean that the casing is or is intended to be removed and that such casing may be removed because of formation of a secondary “skin” of coagulated proteins on the surface of the frankfurter. This secondary skin forms the outer surface of the so called “skinless frankfurters”. Skin formation is known to be produced by various means including the traditional smoke curing with gaseous smoke, low temperature drying, application of acids such as citric acid, acetic acid or acidic liquid smoke or combinations thereof. Desirably, this secondary skin will be smooth and cover the surface of the frankfurter. Formation of a liquid layer between the casing and the frankfurter skin facilitates peeling and relates to the meat emulsion formulation, percent relative humidity during the cooking environment, subsequent showering, and steam application to the chilled frankfurter.
Also, application of certain types of coatings to the inside wall of food casings may improve the release characteristics of the casing from the encased sausage product. Use of peeling aids or release coatings has helped to overcome peelability problems associated with process variables. Following cooking, cooling and hydrating, peeling aids such as water-soluble cellulose ethers help release the casing from the frankfurter skin by formation of a peeling enhancing layer between the casing and the frankfurter skin. See U.S. Pat. Nos. 3,898,348 and 4,137,947 for further examples.
These peeling aid coatings have been used with varying degrees of success to provide cellulosic casings capable of being peeled on high speed machine peelers. Generally such cellulosic casings either with or without peeling aid coatings have an approximately neutral pH with pH values typically falling within a range of about 5.9 to about 8.6.
Use of various transferable colorants on food packaging, including cellulosic casing, has been known for some time. Self-coloring casings are disclosed in U.S. Pat. Nos. 2,477,767; 2,477,768 and 2,521,101. These casings are designed to transfer color to the sausage surface. Such casings are generally either coated or impregnated with food grade water-soluble dyes and have also been made commercially available with nontransferable black or white or colored opaque stripes. Also, liquid smoke impregnated fibrous casings are known to transfer liquid smoke to the surface of sausages encased therein, transferring a flavorant or colorant and also causing a browning reaction on the sausage surface.
U.S. Pat. Nos. 2,477,767 and 2,477,768 disclose regenerated cellulose sausage casings uniformly treated with a transferable, edible natural coloring matter. Included in a list of such materials is annatto. The colorant may be applied with glycerine and/or other polyhydric alcohols or vegetable oil. Orange to orange-red sausages are made using self-coloring casings dyed with synthetic colorants such as coal tar dyes that have been approved by government regulation for use on food. These dyes, which are typically known as FD & C dyes, are typically applied to cellulosic casings by dipping gel stock casing into a tank containing an aqueous mixture of glycerine and the FD&C dyes.
In some markets only natural colorants (derived from biological organisms), such as cochineal, turmeric, annatto and caramel are authorized by law and the use of synthetic (fossil-fuel derived or nonbiologically derived) colorants such as coal tar dyes is not allowed. This is especially true for many South American and Asian markets where use of natural red colorants derived from plants or animals are preferred by custom or law.
Another colorant well known in the art is liquid smoke. Liquid smoke solutions are available in a number of formulations. Previously, standard liquid smoke solutions were known as “as-is” solutions, where the liquid smokes were generally highly acidic within a pH range of about 2.0 to about 2.5 and a titratable acidity of at least 3 wt. %, and also contained tar-like components. When used to treat casings, particularly the external surface of a casing, the tar content caused sticky deposits to accumulate on equipment used to treat the casing. The acidity of the liquid smoke also interfered with the peelability of the casing by interfering with the action of the peeling aid used, such as carboxymethyl cellulose. Over time, the low pH liquid smoke also caused the cellulose to degrade, resulting in pinholes and such in the casing itself. In addition, iron contamination caused dark spots on the processed sausages, which were then unacceptable to the consumer.
It was found that tar could be removed from the liquid smoke by neutralizing the “as is” smoke to precipitate the tar, filtering resulting solids, and by adding polysorbate, which solubilized all remaining tars, thereby eliminating the tarry deposit accumulation problem. Further treatment of the casings containing liquid smoke with sodium dihydrogen phosphate is often used to prevent black spotting on the enclosed foodstuffs caused by the iron contamination. Even partial neutralization of the liquid smoke reduces the cellulose degradation problem, and allows the peeling agents to perform as intended, as described in U.S. Pat. No. 4,540,613, which is incorporated herein by reference.
However, because many sausage manufacturers prefer to have a darker colored sausage than that obtainable by processing the meat, meat emulsion, vegetable mixture, or cheese in nonfibrous casing impregnated with liquid smoke, they stuff clear nonfibrous casing with the foodstuff and later drench the stuffed casing, or the released foodstuff, in liquid smoke. This does result in a darker foodstuff, such as a sausage, but at an additional cost, due to the large amounts of liquid smoke needed for drenching or overshowering. Additionally, the equipment used for providing the liquid smoke needs to be thoroughly cleaned to remove tar deposits from it on a regular basis, which can be once a day.
Casings that are well known in the art to be impregnated and therefore contain liquid smoke are fibrous casings. Because they are fibrous reinforced casings, they can be coated with acidic liquid smoke containing low levels of tars or basic liquid smokes with high levels of tars. Additionally, the pinholing and other damage that happens with nonfibrous casing does not occur, due to the reinforced nature of the fibrous casing. However, fibrous casing is not the casing of choice in the production of many sausages and other foodstuffs when the casing must be removed after processing. But where fibrous casing is the casing of choice, enhancement of the smoky red coloring imparted by or through the fibrous casing is often desired by manufacturers, albeit only at low additional costs in processing.
It is an objective of this invention to provide a method of producing sausages and other foodstuffs having good flavor and an acceptably dark smoky color, without the need for using wasteful and expensive amounts of liquid smoke.
All patents cited herein are hereby incorporated by reference.